Liquid dosing device

ABSTRACT

A device ( 2 ) for fitting to the neck of a deformable bottle ( 4 ) to give a metered dose of liquid when the bottle is squeezed. The liquid dispensed through outlet ( 30 ) has to pass through a metering chamber ( 34 ) in which it is directed around or through a freely-moving shuttle ( 8 ), movement of the shuttle ( 8 ) with the flow being resisted by the creation of a partial vacuum in the expanding control chamber ( 42 ) behind the shuttle, so that the rate at which the shuttle moves to the outlet end of the metering chamber ( 34 ) to close the outlet ( 30 ), and hence the amount of liquid dispensed, is controlled by the rate at which liquid can enter control chamber ( 42 ). Because it is configured so that all the liquid enters metering chamber ( 34 ) at its inward end, the chamber may fitted either inside or outside the neck of the bottle ( 4 ) and the dose may be adjusted by moving the outlet ( 30 ) closer to, or further from, the inlet.

This invention relates to a device for delivering a metered dose ofliquid from a squeezable bottle. As used herein, ‘squeezable bottle’means any closed container for holding liquid products which istemporarily deformable by manual pressure.

There are various known liquid metering devices for squeezable bottles,in which there is a metering chamber having a single outlet but two setsof inlets. To avoid repetition, where the terms ‘inlet’ and ‘outlet’ areused, they can refer to a set of openings as well as a single one. Themain flow of liquid, which enters the chamber by one inlet, is initiallyfree to flow directly out of the outlet. A pilot flow of liquid, whichenters the chamber through the other inlet, drives an obturatingcomponent, commonly a ball, along the chamber until it closes off theoutlet. As the ratio of main to pilot flows can be quite large, thisarrangement is potentially capable of dispensing a large dose through arelatively small chamber. Devices of this type are described in U.S.Pat. No. 3,146,919, filed in 1960, and U.S. Pat. No. 3,567,079, filed in1968, and in GB 2201395, filed in 1986.

Although each of these inventions should be capable of deliveringaccurately metered doses of a given liquid, none appears to have foundwide acceptance. In the case of the last named patent, of which I wasco-inventor, this is because the dose has been found to be constant onlyso long as there is no variation in either the viscosity or the surfacetension of the liquid being dispensed or in the force with which thebottle is squeezed. The same is probably true of the other twoinventions.

Apart from inconsistency of dose, the fact that all of the above devicesrequire inlets at both ends of the device means that they all sufferfrom the following inherent limitations: (a) they have to be configuredso that they fit within the neck of the bottle, rather than be attachedto the outside, (b) they can only provide a user-selectable dose bychanging the ratio of pilot to main inlet sizes, which is mechanicallydifficult as well as of doubtful accuracy, (c) they need a separatemeans of sealing the outlet to make the package ‘shippable’ and (d) theycannot completely empty the bottle.

The present invention differs from all the above devices in that it hasall inlets to the device at the opposite end from the outlet. This notonly simplifies the flow paths so allowing much better control of theflow ratios and hence much better consistency of dose but also (a)allows the device to be fitted either inside or outside the bottle, (b)the dose can be varied easily and accurately by altering the stroke, (c)the stroke can be reduced to zero, which effectively seals the outletand (d) the bottle can be almost completely emptied as there is no needto provide a passageway around the metering chamber to the ports at theoutlet end.

Essentially the invention comprises a liquid dosing device for fittingto the neck of a squeezable bottle comprising a metering chamber havingan inlet or inlets at its inward end to connect its interior to theinside of the bottle and an outlet or outlets at its outward end throughwhich liquid is dispensed, the chamber being divided into two by afreely-moving shuttle, which falls to the inlet end of the chamber whenthe bottle is upright, the chamber and shuttle being so configured that,when the bottle is inverted and then firmly squeezed, liquid which isforced into the metering chamber is divided into a main flow componentwhich passes through or around the shuttle but substantially by-passesthe chamber behind it, this flow then being discharged through theoulet(s), and a pilot flow component which is fed into the chamberbehind the shuttle but is substantially prevented from passing to theoutlet side of the shuttle, so that although the shuttle tends to bemoved by the viscous drag or impact of the flow of liquid upon it, anysuch movement expands the chamber behind it, thus creating a partialvacuum within it which prevents the shuttle expanding the chamber fasterthan the pilot flow can fill it, and therefore the ratio of main topilot flow components determines the rate at which the shuttle will moveand hence how much liquid is dispensed before the shuttle reaches thefar end of the metering chamber, where it occludes the outlet(s) andprevents any further dispensing of liquid until the process is repeated.

Preferably, the main flow component constitutes the major portion of thewhole flow of liquid forced into the metering chamber and the pilot flowconstitutes a minor portion.

The metering chamber is most preferably cylindrical.

In a simple embodiment, the chamber and shuttle are both of circularcross-section, the shuttle being in the form of a piston which allowslittle if any flow past its periphery but has a central hole which is inalignment with the inlet to the chamber and out of alignment with theoutlet, the outlet preferably being at least as large as the inlet, andboth being at least as large as the hole through the shuttle. When thebottle is inverted and squeezed most of the liquid (i.e. the main flow)passes straight through the shuttle and thence out of the spout but aproportion of the liquid (i.e. the pilot flow) is trapped behind theshuttle and gradually carries it forward, the ratio of hole sizesdetermining how much liquid is dispensed before the shuttle reaches thespout end of the metering chamber and closes off the outlet hole.

Experiment has shown that an embodiment of this type can have a highmagnification ratio (up to 5:1 or more) and dispense the same dose (towithin plus or minus 10%), regardless of normal manufacturing changes inthe properties of the product being dispensed or of who squeezes thebottle, provided it is squeezed fairly firmly. Unlike other forms ofmagnifying doser, the components may be very simple mouldings, withoutthe need for very close tolerances. Other features found in few if anyalternatives are (a) the ability to alter the dose by varying thestroke, (b) complete emptying of the bottle and (c) rapid resettingafter a dose has been dispensed.

By way of example, some embodiments of the invention are described belowwith reference to the drawings, all of which are verticalcross-sections, showing the device attached to the neck of a bottle(most of which is not shown) by conventional means (which are notdescribed but may be a snap fit as shown or a screw thread). Fordescriptive purposes ‘up’ and ‘down’ refer to the orientation when thebottle is upright and all components are assumed to be substantiallycircular in plan, as this is the most likely (though not essential) formin practice. Relevant details of the drawings are as follows:

FIG. 1 shows a simple embodiment mounted on the outside of a bottle inthe upright, i.e. non-operating, position, in which both main and pilotflows are directed through the shuttle but are not physically divided,

FIG. 2 shows the same embodiment after the bottle has been partlyinverted and while it is being squeezed,

FIG. 3 shows the same embodiment when the shuttle has reached the end ofits stroke and has closed the outlet,

FIG. 4 shows an embodiment in which the shuttle incorporates a hollowspigot which physically divides the main and pilot flows as they enterthe doser and in which the functional parts are mounted within the neckof a bottle and have a hinged cap that can be closed to seal the outlet,

FIG. 5 shows the same embodiment as in FIG. 4 while a dose is beingdischarged,

FIGS. 6 to 8 show a similar embodiment to that shown in FIG. 1 exceptthat the length of the metering chamber can be altered from one thatgives a maximum dose, as shown in FIG. 6, through a reduced dose (FIG.7) to zero dose (FIG. 8),

FIG. 9 shows an embodiment in which the shuttle is sealed to the sidesof the metering chamber by a flexible diaphragm,

FIG. 10 shows an embodiment in which the main flow is directed aroundthe shuttle,

FIG. 11 shows a similar embodiment but with a one-way valve that allowsthe shuttle to be reset quickly, and

FIG. 12 shows an embodiment which is similar to that shown in FIGS. 1 to3 except that the main flow is passed through the shuffle by a fixedhollow spigot and the pilot flow is directed through a separatepassageway into the chamber behind the shuttle.

With reference to FIG. 1, a dosing device 2 is mounted on the neck of asqueezable bottle 4, the device comprising three components, body 6,shuttle 8 and core 10, all of which may be injection-moulded from rigidplastic materials and each of which is essentially in the form of aninverted cup, having a downwardly-extending skirt and a closed top. Thethree components fit one within the other. The innermost one is core 10,which resembles a conventional closure cap in that its skirt 12incorporates the means of attaching it to the neck of the bottle and itstop 14 forms a seal 16 around the top of the neck. Unlike a closure,however, it has a centrally-located hole 18 through it and skirt 12 hasan outwardly-extending flange 20 to which body 6 is attached. Hole 18 isco-axial with a hole 22 in the top 24 of shuttle 8, whose skirt 26 is aclose but clearance fit around core skirt 12 and, when shuttle top 24 isin contact with core top 14, shuttle skirt 26 extends almost to the topof core flange 20. The top 28 of body 6 has an offset outlet hole 30 andits skirt 32 is a close but clearance fit around shuttle skirt 26 but atight fit on core flange 20. Between them core 10 and body 6 enclosemetering chamber 34, which extends upwards from the upper surface ofcore top 14 to the underside of body top 28, and an annular recess 36,which extends downwards from the core top 14 to flange 20. The clearance38 between shuttle skirt 26 and the sides of recess 36 is justsufficient to allow shuttle 8 to fall freely under gravity from one endof chamber 34 to the other, when the device is inverted without anyliquid in it. The upperside of shuttle top 24 and the underside of bodytop 28 are both flat and square to the axis of the device so that whenthey are in contact with each other they completely seal off body outlet30 from any flow coming either through the shuttle via hole 22 or aroundit via clearance 38.

Shuttle hole 22 may be slightly smaller in diameter than core hole 18 sothat there is a narrow annulus 40 on which liquid pressure can act whenthe bottle is inverted and then firmly squeezed, as shown in FIG. 2.Most of the flow passes straight through shuttle hole 22 but even if itis no smaller than core hole 18, the viscous drag of the liquid on thesides of hole 22 will tend to carry shuttle 8 with it. Any movement ofthe shuttle, however, will be resisted by the drag of shuttle skirt 26in recess 36 and by the partial vacuum that is created in controlchamber 42 that develops behind the shuttle. As clearance 38 is small,the vacuum must be mainly satisfied by flow through core hole 18 and, ifthe opposing drag properties are properly balanced, the proportion ofthe flow that is required to satisfy the vacuum will remainsubstantially constant, regardless of how hard the bottle is squeezed.This means that by the time the shuttle reaches the end of its strokeand closes outlet 30, as shown in FIG. 3, the volume of liquid that hasbeen discharged through the outlet will be in a fixed relationship tothat which has filled chamber 42, i.e. the dose will stay constant.

When the bottle is returned to upright and pressure on it released, apartial vacuum is formed in the bottle which assists gravity inresetting shuttle 8 back to the position shown in FIG. 1.

The embodiment shown in FIGS. 4 and 5 also comprises three components,body 6 a, shuttle 8 a and core 10 a, but in this case the functionalparts of the doser are accommodated inside the neck of the bottle, body6 a having an outer skirt 44 which incorporates a thread or otherconventional means of securing the device to the bottle. It alsoincorporates an integrally-hinged lid 46 which can seal the outlet.Shuttle 8 a is enclosed within body skirt 32 a, the open end of which isclosed by core 10 a. The core has central bore 18 a which surrounds ahollow spigot 48 extending downwardly from shuttle 8 a, leaving anannular passage 50 between them. The spigot physically divides the flowthrough core inlet 18 a into a main component which passes through itscentral bore 22 a and thence out of outlet 30 a and a pilot componentwhich passes along annular passage 50 into chamber 42 a behind theshuttle. As this arrangement gives much a greater area on which the flowacts to drag the shuttle forward, the drag opposing motion may also beincreased by the addition to the shuttle of a number of inner skirts 52,which fit into mating recesses 54 formed in core 10 a. The number anddepth of these mating skirts and recesses can be varied to produce agood balance between the drag forces operating on the shuttle; they alsoconstitute a labyrinth that reduces the flow of liquid leaking past it.

Both the embodiments described above have a fixed dose and require someform of cap (to seal off the outlet and make the package ‘shippable’)but in the version shown in FIGS. 6 to 8, which requires no more parts,body 6 b can be moved relative to core 10 b from a position in whichmetering chamber 34 b (and hence the dose) is maximised, as shown inFIG. 6, via any number of intermediate positions, such as that shown inFIG. 7, which give smaller doses, to the one shown in FIG. 8, in whichthe dose is reduced to zero. In this position the outlet is permanentlyclosed off, so there is no need for a ‘shipping’ cap. Aninwardly-directed annular bead 56 at the base of the body 6 b engageswith the bottom edge 58 of the core to hold the body in the closedposition and with one of a series of annular grooves 60 to hold it in aselected dosing position. The underside of body top 28 b and top 24 b ofthe shuttle both taper inwardly downwards so that any product remainingin chamber 34 b drains back through shuttle hole 22 b and is notsquirted out of outlet 30 b when the body is pushed down to the closedposition.

In all the above embodiments, leakage past the shuttle has beenminimised by some form of labyrinth seal between the shuttle and themetering chamber but, in the embodiment shown in FIG. 9, this leakage iscompletely eliminated by a flexible membrane 62 (which could be formedintegrally with shuttle 8 c) and sealed to the sides of metering chamber34 c by being trapped between body 6 c and core 10 c. In thisembodiment, which is shown just after the bottle has been inverted andsqueezed, central hole 22 c does not pass straight through the shuttlebut connects with oblique passages 64 that pass the main flow intometering chamber 34 c in such a way that outlet 30 c can be centrallylocated rather than offset.

In the embodiment shown in FIG. 10, it is inlet hole (or holes) 18 dwhich is offset and leads directly into annular recess 36 d between theskirts 12 d and 32 d of core 10 d and body 6 d respectively, the flowbeing divided by the skirt 26 d of shuttle 8 d into a main component,which passes around the outside and thence via metering chamber 34 d tocentral outlet 30 d, and a pilot component, which passes on the insideinto control chamber 42 d.

As there is no separate outlet from control chamber 42 d, it may take along time to empty when the bottle is returned to upright but in theembodiment shown in FIG. 11, which is in all other respects similar tothat shown in FIG. 10, a ball valve 66 opens drain back port 68 when thebottle is upright, as shown, to allow the chamber to empty rapidly andreset the device.

The embodiment shown in FIG. 12 is exactly the same as that shown inFIGS. 1 to 3 except that a hollow spigot 69 extends from the centre ofcore 12 e through central hole 22 in shuttle 8 to within a shortdistance of end face 28 of body 6 so that the main flow is fed into themetering chamber 34 close to outlet 30. The pilot flow is fed intocontrol chamber 42 behind shuttle 8 via a separate hole 70 in top 14 eof core 12 e. As the clearance between spigot 69 and shuttle hole 22 isminimal, the main and pilot flows are almost completely separated andthe ratio between them should therefore be more constant than when theycan mingle.

1. A liquid dosing device for fitting to the neck of a squeezable bottlecomprising a metering chamber having an inlet or inlets at its inwardend to connect its interior to the inside of the bottle and an outlet oroutlets at its outward end though which liquid is dispensed, themetering chamber being divided by a freely-moving shuttle into an inletchamber on the inlet side of the shuttle and an outlet chamber on theoutlet side of the shuttle falling to the inlet end of the meteringchamber when the bottle is upright, the chamber and shuffle being soconfigured that, when the bottle is inverted and then squeezed, liquidwhich is forced in the metering chamber has a main flow component whichpasses through or around the shuttle and into the outlet chamber butby-passes the inlet chamber behind the shuttle, this flow then beingdischarged through the outlet(s), and a pilot flow component which isfed into the inlet chamber behind the shuttle but is prevented frompassing into the outlet chamber, so that although the shuttle tends tobe moved by the viscous drag or impact of the flow of liquid upon it andsuch movement expands the inlet chamber behind it, the inlet chamberexpands only as fast as the pilot flow can fill the expanding inletchamber such that the ratio of main to pilot flow components determinesthe rate at which the shuttle will move and hence how much liquid isdispensed before the shuttle reaches the far end of the meteringchamber, where it occludes the outlet(s) and prevents any furtherdispensing of liquid until the process is repeated.
 2. A dosing deviceas claimed in claim 1 wherein the main flow component constitutes themajor portion of the whole flow of liquid forced into the meteringchamber and the pilot flow constitutes a minor portion.
 3. A dosingdevice as claimed in claim 2 in which there is a passage through theshuttle but a peripheral seal prevents any significant flow around it.4. A dosing device as claimed in claim 3 in which the peripheral seal isa flexible membrane.
 5. A dosing device as claimed in claim 1 in whichthere is a passage through the shuttle but a peripheral seal preventsany significant flow around it.
 6. A dosing device as claimed in claim 5in which the peripheral seal is a flexible membrane.
 7. A dosing deviceas claimed in claim 5 in which the shuttle seal is a labyrinth formedbetween the walls of the shuttle and those of the metering chamber.
 8. Adosing device as claimed in claim 5 in which the shuttle seal is alabyrinth formed between the walls of the shuttle and those of themetering chamber.
 9. A dosing device as claimed in claim 1 in which themain flow component and the pilot flow component are conducted alongseparate passageways.
 10. A dosing device as claimed in claim 1 in whichthe main flow component is not physically separated from the pilot flowcomponent.
 11. A dosing device as claimed in claim 10 in which themetering chamber and shuttle are both of circular cross-section, theshuttle having a central hole which is in alignment with the inlet tothe chamber and out of alignment with the outlet, the outlet being atleast as large as the inlet, and both being at least as large as thehole through the shuttle.
 12. A dosing device as claimed in claim 1 inwhich the distance between the inlet and outlet may be altered to varythe size of the dose or close the outlet.
 13. A dosing device as claimedin claim 1 in which the device is fitted with an integral or removablelid.
 14. A dosing device as claimed in claim 1 wherein the meteringchamber is cylindrical.